Emplacement of the Franklin large igneous province and initiation of the Sturtian Snowball Earth.
- Judy Pu
University of California, Santa Barbara
During the Cryogenian (720-635 Ma) Snowball Earth glaciations, ice extended to sea-level near the equator. The cause of this catastrophic failure of Earth’s thermostat remains unknown, but the near coincidence of snowball onset with one of the largest magmatic episodes in the geological record, the Franklin large igneous province, suggests a causal relationship. New U-Pb geochronology on zircon and baddeleyite from sills associated with the paleo-equatorial Franklin large igneous province in Arctic Canada record rapid emplacement ~0.9-1.6 Myr before the onset of widespread glaciation. Geologic observations and (U-Th)/He dates on Franklin sills are compatible with major post-Franklin exhumation, possibly due to development of mafic volcanic highlands on windward equatorial Laurentia and increased global weatherability. After a transient magmatic CO2 flux, long-term carbon sequestration associated with increased weatherability could have nudged the Earth over the threshold for runaway ice-albedo feedback.
Негізгі бет Emplacement of the Franklin large igneous province and initiation of the Sturtian... - Judy Pu
Пікірлер: 1